硫酸改性活性炭对Li~+吸附的影响

以不同浓度的硫酸对活性炭进行酸化处理,并考察活性炭添加量、改性方式对Li⁺吸附效果的影响,同时与未处理的活性炭进行比较。结果表明,利用H_2SO_4、改性活性炭的吸附效果最佳条件为40%H_2SO_4,改性时间6 h,改性温度60℃,吸附量与原炭相比提升了1.54 mg/g。在锂离子浓度为100 mg/L的溶液中加入活性炭,当添加量为0.6 g时,去除率最大为85.6%,同等投加量下与原炭相比,去除率提升了15.2%。     

活性炭和改性活性炭对六价铬吸附行为的研究

采用二苯炭酰二肼分光光度法研究了活性炭和用HNO3改性的活性炭对水中铬离子的吸附行为,研究了不同时间不同吸附剂用量及不同pH值对铬离子的吸附效果,从而得到处理铬废水的最佳条件。实验结果表明:改性活性碳对铬离子吸附效果较好,pH值为3,吸附时间80min是较为经济且除去率最高的条件。研究结果可为含铬废水的处理提供理论基础及技术支持。     

改性活性炭对溶菌酶吸附性能的影响

采用KOH热处理方法对沥青基球形活性炭进行改性,并通过BET、Zeta电位和XPS对活性炭进行表征。利用溶菌酶模拟中分子尿毒症毒素β2-微球蛋白,测定改性前后活性炭对溶菌酶的2 h吸附率,从而推测对β2-微球蛋白的吸附能力。同时,探究了改性条件对活性炭吸附性能的影响。结果表明,2 h内未改性的活性炭吸附率为42.54%,改性活性炭吸附率最高可达76.54%,提高了83.19%。Zeta电位和活性炭中9～80 nm范围内的孔容是影响活性炭对溶菌酶吸附性能的因素,整个吸附过程主要由孔结构和静电作用控制。     

改性活性炭吸附除砷的研究

以小麦秸秆、木屑、煤渣等所制备的活性炭及其活性炭负载铁作为吸附剂,用于水中As（Ⅲ）的去除。考察了活性炭种类、吸附时间、吸附温度、溶液pH值和吸附剂投加量等对As（Ⅲ）去除的影响。结果表明,木屑制备的活性炭所负载铁作为吸附剂,对水中As（Ⅲ）的去除效果最好;As（Ⅲ）的去除率随吸附时间、吸附温度、溶液pH值和吸附剂投加量的增加而增加。     

改性活性炭吸附芳烃的研究进展

从改性活性炭出发,介绍热处理、微波等物理改性以及氧化、气相还原、酸碱液相处理、金属离子改性等化学改性方法对活性炭的影响。总结活性炭孔道结构、比表面积、化学性质对吸附不同芳烃的影响。结果表明,活性炭的孔道结构、比表面积和表面化学性质共同影响单环芳烃吸附效果;孔道结构和比表面积影响多环芳烃吸附较多,表面化学性质影响相对较少。     

改性活性炭对染料废水的吸附性能研究

采用化学氧化改性活性炭来处理染料废水,通过Boehmd官能团滴定法、扫描电子显微镜以及傅里叶红外光谱仪对活性炭的含氧官能团和微观结构进行研究。分析了改性活性炭在不同的投加量、初始浓度、吸附时间、温度、溶液p H值等反应条件下对亚甲基蓝溶液吸附效果的影响。结果表明:随着硝酸体积分数的增大,改性活性炭所含含氧官能团越多,孔结构越明显;当活性炭的投加量为0.5g,亚甲基蓝溶液的浓度为15 mg/L,时间为210 min时,吸附接近平衡,随着溶液p H的升高,活性炭对亚甲基蓝的去除率提高,最高可达88.3%。     

改性活性炭吸附低浓度甲烷的研究

考察了低浓度甲烷在不同种类吸附剂上的动态吸附性能,结果发现活性炭类吸附剂对甲烷的吸附性能较好。以椰壳活性炭为吸附剂,考察了高温热处理、氨水改性及金属改性对活性炭甲烷吸附性能的影响。实验表明,对活性炭进行高温热处理、氨水处理后其甲烷吸附性能降低,金属改性对甲烷吸附性能的影响视金属的种类而定。     

氢氧化镁改性活性炭对铜离子的吸附

采用反应结晶技术制备了改性活性炭材料(Mg-GAC)，并采用 SEM、XRD表征手段对改性前后活性炭进行微观分析，进而研究了 GAC 和 Mg-GAC随吸附时间、溶液pH值和温度变化对废水中铜离子的吸附效果影响。结果表明，GAC经改性后，大大增加了其比表面积，增至738.01m2/g。在Mg-GAC 投加量为0.3g，铜离子浓度为40mg/L，温度为25℃，pH为7的条件下反应2 h，其吸附量达到11.66mg/g。另外，铜离子的吸附过程符合 Langmuir 等温模型。     

活性炭的改性条件及其对硫化氢吸附性能的影响

以工业活性炭为载体制备改性活性炭,对比研究了未改性活性炭,NaOH、Na2CO3、Fe(NO3)3、Cu(Ac)2改性活性炭及挂膜硫氧化细菌后活性炭在相同条件下对硫化氢穿透时间及吸附容量的影响。结果表明：在相同控制条件下,NaOH改性活性炭明显优于其它改性剂;不同梯度改性剂条件下,20% NaOH改性活性炭对硫化氢的吸附效果最好,吸附穿透容量为78.25 mg/g,穿透时间可以达到2000 min以上;不同改性剂挂膜硫氧化细菌后对硫化氢均有一定的处理效果,其中对已达到饱和吸附的NaOH改性活性炭挂膜后的再生效果可以达到100%以上,说明挂膜硫氧化细菌活性炭对硫化氢的处理具有很好的效果。     

Effect of surface properties of activated carbons on surfactant adsorption kinetics

This research investigates the adsorption properties of three activated carbons (AC) derived from coconut, coal, and wood origin. A linear relationship exists between the number of water molecules adsorbed onto each AC and the oxygen content determined elemental analysis and XPS. An inverse linear relationship exists between the plateau amount of dodecanoic acid anionic surfactant and the oxygen content on the surface of ACs. The surface charge on each AC’s surface had a linear relationship with the plateau amount of dodecanoic acid. A plug-flow heterogeneous surface diffusion model (PFHSDM) for a fixed-bed adsorption process was developed to describe the adsorption kinetics in a fixed-bed column. The model represents axially dispersed plug-flow, external mass transfer, adsorption equilibrium on the fluid-particle interface, and intraparticle diffusion. The larger molecular dimension of the dodecanoic acid as a more hydrophobic entity than octanoic acid led to a faster external mass transfer rate but a slower surface diffusion rate as estimated from the PFHSDM. The interaction between the organic moiety of surfactant and the AC surface chemistry such as surface oxygen content and surface charge contributes to the adsorption performance in both to the adsorption equilibrium and kinetics.     

相对湿度对甲醛在改性活性炭上吸附的影响

This work mainly involves the study of effect of relative humidity on adsorption of formaldehyde on the activated carbons modified with organosilane solution. Modification of activated carbons was carded out by impregnating activated carbon with organosilane/methanol-containing solutions. The breakthrough curves of formaldehyde in the packed beds of original and modified activated carbons were measured, respectively, at relative humidity of 30%, 60%, and 80%. Temperature-programmed desorption （TPD） experiments were used to estimate the activation energy for desorption of formaldehyde from the activated carbon. Results showed that the relative humidity had strongly influence on breakthrough curves of formaldehyde in the packed beds. The higher the relative humidity of gas mixtures through the packed beds was, the smaller the breakthrough time of formaldehyde became. The use of organosilane compounds to modify surfaces of the activated carbon can enhance the interaction between formaldehyde and the surfaces, and as a result, the breakthrough times of formaldehyde in the packed beds of the modified activated carbon were longer than that in the packed bed of the unmodified activated carbon.     

Iodine adsorption and structure of activated carbons

Studies were conducted on the adsorption of iodine from saturated aqueous solutions and from saturated vapor by eight activated carbons of greatly diverse pore structures. Water adsorption data were used to determine the pore size distribution curves which provided both the distributions of the pore constriction (desorption) and cavity (adsorption) diameters. Adsorption from aqueous phase formed a unimolecular layer on the carbon surface while adsorption from saturated vapor produced pore-filling of micropores (pores less than 30 Å diameter) and surface coverage of the macropores. A great deal of steric interference was present because of the small difference in the diameter of iodine molecule (4.94 Å) relative to the 10–30 Å diameter pores. Good correlation was attained between adsorption and pore structure when corrections were made for the steric effect and the mean diameter distributions of the constrictions and cavities were used. The model for the iodine-on-carbon adsorption resembles packing of spheres into cylinders.     

Influence of activated carbons porous structure on iopamidol adsorption

In the present study the adsorption of iopamidol (a pharmaceutical compound used in soft tissues diagnostic imaging based on X-ray radiography) onto activated carbons was assessed, since this is an effective technology to remove pharmaceutical compounds that fail to be degraded in conventional wastewater treatments. Three sisal-based carbons prepared by chemical activation with KOH, and two commercial carbons, were selected in order to understand the role of the porous structure in the removal of iopamidol from aqueous phase. The kinetic and equilibrium adsorption results indicate that iopamidol is adsorbed in mesopores and also in larger micropores (supermicropores). The adsorption isotherms reflect a complex mechanism originating unusual two-step isotherms, which highlights the influence of the porous structure. As proven using conductivity measurements and computational calculations, iopamidol can be adsorbed as a single molecule or in the form of aggregates, filling either small or much larger pores in a discontinuous way. By conjugating the molecular dimensions of the iopamidol species and the micropore size distribution of the samples, it was demonstrated that the unusual two-step isotherms are related with the absence of pores with width between 1.2 and 2.0 nm.     

Co改性活性炭吸附NO的实验研究

采用Co(NO_3)_2对活性炭进行改性,考察浸渍浓度和吸附温度等条件对活性炭吸附NO性能的影响,并对已吸附NO的0.3 mol·L~(-1)的Co(NO_3)_2改性活性炭进行再生。通过BET、SEM、吸附等温线和FT-IR表征样品的比表面积、颗粒形貌和表面官能团。结果表明,当浸渍溶液浓度为0.3 mol·L~(-1)时,吸附效果最佳,80 min时吸附效率达88.90%。活性炭的吸附效率随着温度升高而降低,用0.3 mol·L~(-1)Co(NO_3)_2改性的活性炭在200℃时的吸附效率大于90%,并可持续50 min。SEM和FT-IR表征结果表明,在Co(NO_3)_2改性的活性炭表面和孔隙生成了Co_3O_4,促进NO催化氧化为NO_2并进行吸附。加热再生后的0.3 mol·L~(-1)Co(NO_3)_2改性活性炭对NO的吸附效率在60 min内仍高于88.90%,再生效果较好,可持续再生利用。     

Spherical activated carbons for low concentration toluene adsorption

The activation process of a spherical activated carbon (SAC) from Kureha Carbon was analysed and the behaviour of these materials to adsorb low concentration volatile organic compounds was studied. Two series of activated carbons were prepared using CO₂ or steam as activating atmospheres at 880 and 840 °C, respectively. Activation times between 45 min and 24 h were selected, leading to burn-offs between 21 and 60%. The results show, for similar burn-off percentages, that the porosity development is similar for the two activating gases at moderate burn-off percentages, and larger for CO₂ than for steam at high burn-off percentages. For similar burn-offs, steam leads to SACs with slightly larger bed densities than CO₂. In general, a low and similar increase in the total surface oxygen groups’ content is noted after activation with both activating agents. Toluene adsorption capacities as large as 46 g toluene/100 g SAC can be achieved with some of these spherical activated carbons in a continuous flow-through SAC bed, when influent air-phase toluene was 200 ppmv. Considering that these SACs have quite high bed densities, their toluene adsorption capacities per unit of volume reach remarkably high values.     

D751树脂对锂离子的吸附性能及机理

为了掌握D751树脂对Li+的吸附行为,通过静态和动态吸附实验研究D751树脂对Li+吸附性能的影响因素,从动力学方面对吸附过程进行分析,并通过红外光谱探讨吸附机理。结果表明,吸附过程符合单分子层吸附的Langmuir等温吸附方程,升高温度和pH值均有利于吸附过程;在静态实验中,D751树脂吸附行为符合二级反应动力学模型,控制步骤为膜扩散控制,对Li+吸附交换反应1h即可达到平衡;动态实验中,提高转速以及低流速有利于吸附过程,树脂具有很好的再生性能,并且操作简单,有望用于锂的提取与富集。     

Water vapour adsorption on lignin‐based activated carbons

Lignocellulosic wastes are interesting precursors for carbon products. The high amount of Na observed in kraft lignin makes it a promising precursor for the preparation of activated carbons for desiccant applications. Water adsorption capacity and kinetics of kraft lignin‐based chars and activated carbons with different burn‐off and inorganic matter content have been studied. CO₂ partial gasification of lignin char develops a wide porous structure. An increase of the micropore volume can be observed at low to medium burn‐offs. At degrees of higher activation the mesoporous structure develops. For very high burn‐off the porous structure is destroyed by coalescence of the pores and reduction of the carbon material. The carbons obtained show atomic surface concentrations of sodium from 7.6–15.4%, as revealed by XPS analysis. Water vapour adsorption isotherms have been obtained in a thermogravimetric system and have been fitted by a DS model, which properly represents the experimental data. The kinetics of water vapour adsorption follows a linear driving force mass transfer (LDF) model. The presence of sodium and oxygen surface groups on the carbon surface enhances water vapour adsorption at low relative pressure. Activated carbon produced at 41% burn‐off shows the highest water vapour adsorption at low relative pressures, as a consequence of the high sodium dispersion on its surface. The sodium dispersed over the carbon surface undergoes clustering as gasification proceeds, decreasing the number of active centres. For burn‐off higher than 41%, this behaviour produces a decrease in the water adsorbed at low relative pressures. Copyright © 2007 Society of Chemical Industry     

A comparison of adsorption characteristics of various activated carbons

The physico-chemical characteristics of activated carbons obtained from different agricultural by-products by pyrolysis in a stream of water vapor have been investigated. It was established that under the same conditions of treatment the physico-chemical and adsorption characteristics of activated carbons depend on the composition of the initial raw materials. Activated carbon obtained from apricot stones has the best properties. It is characterized by a large specific surface area and micropores volume and high iodine and methylene blue adsorption activity. The activated carbons produced from cherry stones and grape seeds are characterized by predominating meso- and macropores structure. It can be supposed this is related to the larger content of lignin in those materials.